Can A Child Fly After Suffering From Severe Concussion?

Hi. My 7 year old son just suffered a severe concussion on the ski fields in Canada- initially, they thought he may have broken his neck. Having arrived at the hospital, he had regained consciousness and the doctor there was reluctant to give him a CAT scan because of his age. He is now at the hotel with us, but is hardly talking and is very very tired. We are due to fly to Australia tomorrow and whilst the doctor at the hospital said he should be ok, the doctor on the slopes said he shouldn't fly. What would you suggest ?